Global climate cooling spurred skipper butterfly diversification

Characterizing drivers governing the diversification of species-rich
lineages is challenging. Although butterflies are one of the most
well-studied groups of insects, there are few comprehensive studies
investigating their diversification dynamics. Here, we reconstruct a
phylogenomic tree for ca. 1,500 species in the family Hesperiidae, the
skippers, to test whether historical global climate change, geographical
range evolution, and host-plant association are drivers of
diversification. Our findings suggest skippers originated in Laurasia
before the Cretaceous-Paleogene mass extinction, in a northern region
centered on Beringia before colonizing southern regions coinciding with
global climate cooling. Climate cooling also fostered the diversification
of skippers throughout the Cenozoic possibly by fueling biome transitions
from closed to open ecosystems such as grasslands. An early shift from
dicot-feeding to monocot-feeding reduced extinction rates and increased
speciation rates, explaining the large diversity of grass-feeding adapted
skippers. A dynamic geographic range evolution and host-plant shifts
linked with long-term climate change explain skipper butterfly
diversification.